1. Field of the Invention
The present invention relates to a compound derived from cyclopentadienone, which can be used as a core material for an organic electroluminescence (referred to as ‘EL’, hereinafter) element or for other optical devices, to a preparation method thereof, and to an EL element using the same.
2. Description of the Background Art
Since green light-emitting phenomenon using tris(8-hydroxy-quinolinato)aluminum (referred to as ‘Alq3’, hereinafter) as a light-emitting material has been known by Tang et al. (See Appl. Phys. Lett., 51, p 913 (1987)) of Eastman Kodak, USA, numerous organic compounds for organic EL materials have been developed.
Currently used light-emitting materials are divided into a metal complex such as Alq3 well known as a fluorescent material (See Chem. Lett., p. 593 (1997); and IEEE Trans Electron Devices, 44, p. 1208 (1997)), and a phosphorescent material (See Nature, 403, p. 750 (2000); and Synth. Met., 122, p. 203 (2001)). Various organic compounds have been reported as an organic single molecule light-emitting material or a core material for other organic ELs (See Chem. Rev., 171, p. 161 (1998); Phys. World, 12, p. 27 (1999); J. Mater. Chem., 10, p. 1 (2000); and Mater. Sci. Eng., R39, p. 143 (2002)).
Aside from the organic single molecule light-emitting material, many researches have been conducted on polymer-based light-emitting materials. For example, since professor Friend et al. in Cambridge university of United Kingdom reported first light-emitting phenomenon of poly(phenylenevinylene) (Nature, 347, p. 539 (1990)), a lot of polymer light-emitting materials have been reported (See Angew. Chem. Int. Ed., 37, p. 402 (1998); Nature, 397, p. 121 (1999); Prog. Polym. Sci., 25, p. 1089 (2000); and Adv. Mater., 12, p. 1737 (2000)).
Examples in which a cyclopentadienones or its derivative is used as an organic EL material are exceedingly rare, but there is an example that a cyclopentadienone compound substituted with a phenyl group is used as a light-emitting material (Appl. Phys. Lett., 56, p. 799 (1990)). In addition, there is an example that a polyphenylene group polymer substituted with a plurality of phenyl groups (See J. Polym. Sci., Part B. 4, p. 791 (1966); J. Polym. Sci., Part A-1, 5, p. 2721 (1967); J. Polym. Sci., Part B, 7, p. 519 (1969); Macromolecules, 5, p. 49 (1972); Macromolecules, 28, p. 124 (1995); Macromolecules, 33, p. 3535 (2000)), which is obtained by a polymerization of a compound having bis-acetylene group (or referred to as ‘diethynyl group’) and a compound having bis-cyclopentadienone group (See J. Org. Chem., 28, p 2725 (1963); Chem. Rev., 65, p 261 (1965); J. Org. Chem., 30, p 3354 (1965); and U.S. Pat. No. 4,400,540) through Diels-Alder reaction, is used as a light-emitting material.
However, it has only been reported that such polymers can be applied as a photoreceptor (See U.S. Pat. No. 5,882,829) or as a dielectric (See U.S. Pat. No. 5,965,679) in a microelectronics industry, especially in the field of integrated circuits. That is, there are few known as compounds derived from cyclopentadienone, and there are even fewer examples that such compounds are used as an organic EL material.